[Cocoa] Clean-up: Update comments regarding drawRect override in TabContentsContainerView.

chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm

Index: chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
diff --git a/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm b/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
index 31ed285b3952c22442d71df14d6faab25ef79e33..92707a854eb2d24c3cf8fa9af135ed61b76588cd 100644
--- a/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
+++ b/chrome/browser/ui/cocoa/tab_contents/tab_contents_controller.mm
@@ -118,24 +118,12 @@ class FullscreenObserver : public WebContentsObserver {
   if (theme)
     bgColor = theme->GetNSColor(ThemeProperties::COLOR_NTP_BACKGROUND);
   if (!bgColor)
-    bgColor = [[self window] backgroundColor];
+    bgColor = [NSColor whiteColor];

[miu, 2014/06/06 01:09:10]

The decision (in https://codereview.chromium.org/244043002) was to make the
default whiteColor, so I made this the same as in line 111 above.

   const float kDarknessFraction = 0.80f;
   return [bgColor blendedColorWithFraction:kDarknessFraction
                                    ofColor:[NSColor blackColor]];
 }
 
-// Override -drawRect to fill the view with a solid color outside of the
-// subview's frame.
-- (void)drawRect:(NSRect)dirtyRect {
-  NSView* const contentsView =
-      [[self subviews] count] > 0 ? [[self subviews] objectAtIndex:0] : nil;
-  if (!contentsView || !NSContainsRect([contentsView frame], dirtyRect)) {
-    [[self computeBackgroundColor] setFill];
-    NSRectFill(dirtyRect);
-  }
-  [super drawRect:dirtyRect];
-}
-
 // Override auto-resizing logic to query the delegate for the exact frame to
 // use for the contents view.
 - (void)resizeSubviewsWithOldSize:(NSSize)oldBoundsSize {
@@ -233,8 +221,6 @@ class FullscreenObserver : public WebContentsObserver {
   [contentsNativeView setAutoresizingMask:NSViewWidthSizable|
                                           NSViewHeightSizable];
 
-  // TODO(miu): The following can be removed once we use a CALayer in
-  // TabContentsContainerView.  http://crbug.com/354598
   [contentsContainer setNeedsDisplay:YES];

[miu, 2014/06/06 01:09:10]

I kept this call to setNeedsDisplay since this will cause setNeedsDisplayInRect
(line 150ish above) to re-compute the background color.  This is useful both for
making sure the right background color is set each time a tab is unhidden, as
well as when a user theme settings change may necessitate a change in color.

 
   // The rendering path with overlapping views disabled causes bugs when